Electrohydraulic thermostatic control valve

ABSTRACT

Apparatus and methods for providing fluid such as water at a controlled temperature. In some embodiments, hot and cold fluid is provided to a thermostatically controlled mixing valve, which then provides fluid at a mixed temperature to a plumbing system. The thermostat provides a first loop for closed-loop control of fluid exit temperature, and preferably there is a second, electronically controlled closed loop for adjusting the temperature of fluid exiting the valve. In yet other embodiments the electronic control loop is fail-fixed, such that a loss of electrical communication to the actuator results in the actuator maintaining its last position. In yet other embodiments there is a system including a flow sensor and a recirculation pump such that the temperature of the fluid exiting the valve cannot be adjusted if there is insufficient flow, or if the pump is actuated.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 61/410,057, filed Nov. 4, 2010, entitledELECTROHYDRAULIC THERMOSTATIC CONTROL VALVE, incorporated herein byreference.

FIELD OF THE INVENTION

Various embodiments of the present invention pertain to thermostaticallycontrolled valves, and in particular to such valves using electricalactuation to provide water within a range of temperatures.

SUMMARY OF THE INVENTION

One aspect of the present pertains to an apparatus for providingthermostatically-controlled fluid. Some embodiments include a hot fluidinlet and a cold fluid inlet. Other embodiments include a valve movableover a range of positions to vary the relative mixing of fluid receivedfrom the hot inlet with fluid received from the cold inlet. Yet otherembodiments include a thermostat operably connected to the valve to movethe valve in response to the temperature of the mixed fluid. Still otherembodiments include an electrical actuator operably connected to thevalve to move the valve in response to an electrical signal.

Another aspect of the present invention pertains to an apparatus forproviding thermostatically-controlled fluid. Some embodiments includeproviding a thermostat, an electrical actuator, a source of hotterfluid, a source of colder fluid, and a repositionable mixing valve.Other embodiments include mixing the hotter fluid and the colder fluidwith the mixing valve. Yet other embodiments include flowing the mixedfluid around the thermostat. Still other embodiments includerepositioning the mixing valve by the thermostat in response to theflowing and repositioning the thermostat by the actuator.

Yet another embodiment of the present invention pertains to a system forproviding thermostatically-controlled fluid. Some embodiments include ahotter fluid inlet and a colder fluid inlet. Other embodiments include athermostatically controlled mixing valve receiving fluid from both thehotter inlet and the colder inlet and providing mixed fluid at a fluidexit. Yet other embodiments include a flow sensor located downstream ofthe fluid exit and providing an electrical signal responsive to theamount of fluid flowing past said flow sensor. Still another aspect ofthe present invention pertains to an apparatus for providingtemperature-controlled fluid. Some embodiments include providing anelectronic controller in electrical communication with an electricalactuator, a source of hotter fluid, a source of colder fluid, and anactuatable mixing valve. Other embodiments include mixing the hotterfluid and the colder fluid with the mixing valve to provide mixed fluidat a temperature. Yet other embodiments include changing the temperatureof the mixed fluid with the actuator by the controller and maintainingthe changed temperature if the electrical communication is broken.

It will be appreciated that the various apparatus and methods describedin this summary section, as well as elsewhere in this application, canbe expressed as a large number of different combinations andsubcombinations. All such useful, novel, and inventive combinations andsubcombinations are contemplated herein, it being recognized that theexplicit expression of each of these combinations is unnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the figures shown herein may include dimensions. Further, someof the figures shown herein may have been created from scaled drawingsor from photographs that are scalable. It is understood that suchdimensions, or the relative scaling within a figure, are by way ofexample, and not to be construed as limiting.

FIG. 1 is a schematic presentation of a system for providing water underthermostatic control according to one embodiment of the presentinvention.

FIG. 2 is a scaled cutaway of the valve of FIG. 1.

FIG. 3 is an enlargement of the electrical actuation portion of thevalve of FIG. 2.

FIGS. 4A, 4B, 4C, and 4D show an exploded view of the apparatus of FIG.3.

FIGS. 5A and 5B are orthogonal views of the apparatus of FIG. 4A.

FIG. 6 is a frontal plan view of a system according to anotherembodiment of the present invention.

FIG. 7 is a scaled cutaway of a valve used in the system of FIG. 6.

FIG. 8A is an enlargement of a portion of the valve of FIG. 7.

FIG. 8B is a view of the apparatus of FIG. 8A with some of the internalsof the actuator shown.

FIG. 8C is an exploded view of the apparatus of FIG. 8B.

FIG. 9 is an electrical schematic corresponding to the system of FIG. 6.

FIG. 10A is a screen shot of a graphical user interface according to oneembodiment of the present invention during one state of control.

FIG. 10B is a screen shot of a graphical user interface according to oneembodiment of the present invention during a different state of control.

FIG. 11 is an electrical schematic corresponding to a system accordingto another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates. At least one embodiment of the present inventionwill be described and shown, and this application may show and/ordescribe other embodiments of the present invention. It is understoodthat any reference to “the invention” is a reference to an embodiment ofa family of inventions, with no single embodiment including anapparatus, process, or composition that should be included in allembodiments, unless otherwise stated. Further, although there may bediscussion with regards to “advantages” provided by some embodiments ofthe present invention, it is understood that yet other embodiments maynot include those same advantages, or may include yet differentadvantages. Any advantages described herein are not to be construed aslimiting to any of the claims.

The use of an N-series prefix for an element number (NXX.XX) refers toan element that is the same as the non-prefixed element (XX.XX), exceptas shown and described thereafter The usage of words indicatingpreference, such as “preferably,” refers to features and aspects thatare present in at least one embodiment, but which are optional for someembodiments. As an example, an element 1020.1 would be the same aselement 20.1, except for those different features of element 1020.1shown and described. Further, common elements and common features ofrelated elements are drawn in the same manner in different figures,and/or use the same symbology in different figures. As such, it is notnecessary to describe the features of 1020.1 and 20.1 that are the same,since these common features are apparent to a person of ordinary skillin the related field of technology. This description convention alsoapplies to the use of prime (′), double prime (→), and triple prime (′″)suffixed element numbers. Therefore, it is not necessary to describe thefeatures of 20.1, 20.1′, 20.1″, and 20′″ that are the same, since thesecommon features are apparent to persons of ordinary skill in the relatedfield of technology.

Although various specific quantities (spatial dimensions, temperatures,pressures, times, force, resistance, current, voltage, concentrations,wavelengths, frequencies, heat transfer coefficients, dimensionlessparameters, etc.) may be stated herein, such specific quantities arepresented as examples only, and further, unless otherwise noted, areapproximate values, and should be considered as if the word “about”prefaced each quantity. Further, with discussion pertaining to aspecific composition of matter, that description is by example only, anddoes not limit the applicability of other species of that composition,nor does it limit the applicability of other compositions unrelated tothe cited composition.

FIG. 1 shows a system 20 for thermostatically controlling thetemperature of a mixture of water flows. System 20 includes a valve 30having hot and cold water inlets, 31 a and 31 b, respectively. The twosources of water are mixed within valve 30 and exit from valve 30 fromoutlet 31 c at a temperature intermediate of the hot and cold watertemperatures. The temperature of the water is sensed by a temperaturesensor 98. A signal from sensor 98 is received by electronic controller90, which provides a command signal to electrical actuator 80.

A cutaway view of valve 30 is shown in FIG. 2. Valve 30 includes apiston and liner assembly 34 placed inbetween inlets 31 a and 31 b.Liner 34 b is held in a static position within body 32 of valve 30.Piston 34 a can vertically slide within liner 34 b under the influenceof push rod 46. Push rod 46 is coupled to piston 34 a by a spring 35 bthat is held captive on rod 46 between an interior face of piston 34 aand a fastener. An exterior face of piston 34 a biased in the upwarddirection by a spring 35 a that also pushes against an interior surfaceof body 32. The sliding motion of piston 34 a relative to liner 34 bprovides variable mixing of hot and cold fluids into the interior volumeof piston 34 a.

The position of piston 34 a relative to liner 34 b is established bythermostat assembly 42. Thermostat assembly 42 includes a shroudassembly 47 that receives within it an upper end of push rod 46. Shroudassembly 47 includes a hollow, cylindrical outer member 47 a with anopen end. A flexible metal bellows 48 is placed through the open end andwithin the cylindrical body of shroud 47, with the lower outer diameterof bellow 48 being soldered to opened end 47 a of shroud assembly 47.The uppermost end of push rod 46 is received within the interior ofbellows 48. Therefore, push rod 46 is longitudinally slidable relativeto shroud assembly 47.

An assembly 44 of coils is wrapped around thermostat assembly 42 fromthe upper end (proximate to outlet 31 c) to the lower end (that isreceived within piston 34 a). The interior of coil assembly 44 is influid communication with the interior volume of shroud assembly 47 thatis between the exterior of bellows 48 and the interior pocket of thetube. This differential volume within shroud assembly 47, as well as theinterior of coils 44, are filled with a fluid whose specific densitychanges as a function of temperature. Preferably, this fluid is amixture of various organic fluids.

Coil 44 is exposed to mixed fluids leaving the piston and liner assembly34 prior to exit of the fluid from outlet 31 c. The mixed fluid conductsheat into the fluid within shroud assembly 47 and coils 44. Since thevolume of the fluid is fixed and trapped, changes in the density of thefluid result in a change in pressure within shroud assembly 47. Thepressure within shroud 47 acts on the upper end of bellows 48, whichpresses against the upper end of rod 46. The position of rod 46 (andlikewise the position of piston 34 a) changes as this internal fluidpressure is counterbalanced by the upward biasing of spring 35 a.Therefore, an increase in temperature of fluid surrounding thermostatassembly 42 will result in expansion of the fluid, which will act topush push rod 48 relative to shroud assembly 47. The properties andtrapped volume of the fluid are used to establish the characteristics ofspring 35 a, as well as the relative spacing between the supply slots ofliner 34 b and the receiving slots of piston 34 a.

From the preceding discussion it can be seen that the temperature of themixed fluid varies as a function of the force exerted on push rod 46. Insome thermostatically controlled valves, shroud assembly 47 is held at afixed, but variable position within body 32. As can be seen in FIG. 2,the top of shroud assembly 47 (also the top of thermostat assembly 42)presses against the bottom face of pusher 52. This compression force isa result of forces from the compression of spring 35 a actinglongitudinally to push thermostat assembly 42 upwards. The position ofpusher 52 limits the upward movement of assembly 42. Therefore, anyrelative motion between shroud assembly 47 and push rod 46 (i.e., as aresult of changes in fluid density) results in a change in length fromthe uppermost end of shroud assembly 47 to the lowermost end of push rod46, with a commensurate change in the mixing of hot and cold liquids.

It is also possible for the mixing of hot and cold liquids (as a resultof variable displacement between piston 34 a and liner 34 b) to beestablished by a downward displacement of pusher 52 relative to bonnet54. Bonnet 54 is engaged by threads into body 32. Pusher 52 is able tomove longitudinally within the bore of bonnet 54. In somethermostatically controlled valves, the position of pusher 52 isestablished by a setscrew that is externally adjustable.

Referring to FIG. 3, one embodiment of the present invention includesmeans for remotely fixing the temperature set point of thermostatassembly 42. The components depicted in FIG. 3 are shown in explodedformat in FIGS. 4. In one embodiment, a spring loaded cartridge 60interfaces between pusher 52 and an electric actuator 80. Actuator 80can change the longitudinal position of an axle 82. One end of this axlepresses against a pin 62 that is located within cartridge 60. Thedisplacement of axle 82 is transmitted by pin 62 to a plunger 64 withincartridge 60. The face of plunger 64 presses against the top of pusher52. In this manner, actuator 80 is able to change the longitudinallocation of pusher 52, which thereby changes the balance of forces(i.e., a balance of fluid pressure and force of spring 35 a), whichsubsequently alters the temperature set point for mixing of hot and coldfluids and provides a change in the average temperature of the mixedfluid leaving outlet 31 c.

FIG. 4B shows a cutaway of a cartridge 60 according to one embodiment ofthe present invention. A pin 62 is biased upward (in reference to theorientation of FIG. 4) by a spring 66 located within the body of thecartridge 60. The lowermost end of pin 62 is received within a bore of aplunger 64. A downward force acting upon the uppermost end of pin 62results in downward movement of plunger 64 and compression of spring 66.Releasing the downward force (such as if axle 82 is retracting) resultsin plunger 64 and pin 62 both moving upward under influence of spring66.

FIGS. 5A and 5B show a side, cutaway view and a top plan view of anactuator 80 according to one embodiment of the present invention.Actuator 80 includes an axle 82 that translates longitudinally along theaxis of thermostat assembly 42. Axle 82 is restrained in two directions(but free in the longitudinal direction) by an output pinion gear 85.The longitudinal position of axle 82 is mechanically coupled to therotation of output pinion gear 85. Axle 82 includes a threaded portionalong its outer diameter that meshes with an internally threaded shankof pinion gear 85. As pinion gear 85 rotates, the internal threads ofthe gear, being in mesh with the external threads of axle 82, cause axle82 to translate longitudinally.

Output pinion gear 85 is driven by a gear train that receives an inputspeed and input torque from a worm gear 86 driven directly by a 24 VDCmotor 88. This gear train of actuator 80 converts a high speed, lowtorque input from motor 88 to a low speed, high torque input to thethreads of axle 82.

Although what has been shown and described is an actuator 80 includingan externally threaded axle driven by a pinion gear, and also a wormgear, other embodiments of the present invention are not so constrained.Other types of linear actuation are contemplated.

One aspect of the gear train of actuator 80 is the difficultyencountered in reversing the motion of the gear train by exertion of aforce on axle 82. As can be seen in FIG. 5 a, the external threads ofshaft 82 have a relatively shallow pitch angle. Therefore, pushing orpulling forces on axle 82 are not leveraged into rotational moments thatare great enough to spin output pinion gear 85. Therefore, the reactionforce of thermostat assembly 42 onto axle 82 (such as when an increasein output fluid temperature results in expansion of the fluid within thecoils) results in minimal or no rotational movement of gear 85.Therefore, the coupling of axle 82 and output pinion 85 tend to isolatethe gear train from forces acting on axle 82.

In addition, the gear train of actuator 80 receives input speed andinput torque from a worm gear 86 driving a pinion gear (not shown). Thisconfiguration of gearing also makes unlikely for forces acting on axle82 to cause rotation of motor 88, since rotation of the driven piniongear is unlikely to cause rotation of worm gear 86.

Because of the coupling of axle 82 to pinion gear 85, and further ofworm gear 86 to its driven pinion, the longitudinal position of axle 82tends to be fixed in a position even if no voltage is applied to motor88. Yet another aspect of system 20 is that the set point for thermostat42 (as established by actuator 80) is substantially fixed to a position,even upon failure of the electronics. This fixation is at least partly aresult of the worm gear. It is difficult for the thermostat to rotatethe worm gear by backwards pushing. Therefore, in some embodiments thevalve exhibits a “fail fixed” response—for some failures of theelectronics, the thermostat retains its current position.

Referring to FIG. 1, it can be seen that a temperature sensor 98provides an electrical signal to controller 90. Preferably, controller90 is a digital control, which can be located remotely from valve 30, orlocated on valve 30. An operator establishes a desired set point orupper and lower limits for a set point, via software that is loaded intomemory 92 within controller 90. Controller 90 compares this desired setpoint to the actual temperature as indicated by sensor 98, and providesa signal to motor 88 so as to accomplish a desired change in theposition of thermostat assembly 42. In some embodiments, the controllingsoftware loaded into memory 92 executes a control algorithm in which aproportional-integral-derivative (PID) algorithm is used to generate thecontrol signal to motor 88. Although what has been shown and describedis a digital controller utilizing software, it is also appreciated thatanalog electronic controllers are also contemplated.

FIG. 6 depicts a system 120 according to another embodiment of thepresent invention. In some embodiments, a plurality of components aremounted to a support member 118. The components of system 120 providemeans for a temperature-conditioning water to be provided to a plumbingsystem, and further means for electronically adjusting the temperatureof the water provided to the plumbing system. Preferably, the componentsof system 120 are arranged on support member 118 in fixed relationshipto each other, and adapted and configured to readily interface with aplumbing system such that only simple fluid connections and simpleelectrical connections need to be made. In some embodiments, the onlyelectrical connections are for providing power to a motorized pump, andfor providing electrical communications with a computer network

System 120 includes inlets 121 and 122 for hot and cold water,respectively. Further, water that has been temperature-conditioned isprovided to a plumbing system from a conditioned outlet 128. Waterreturned from the plumbing system is provided to a recirculated flowinlet 123. A portion (such as 10%) is discharged from system 120 from arecirculating return line 125. Water from the hot and cold outlets 121and 122 is provided to the respective hot and cold inlets 131 a and 131b of a thermostatically controlled valve 130. Temperature-conditionedwater from this valve (shown in FIG. 7) is provided to a valveconditioned outlet 131 c, past a flow sensor 196, and out of conditionedoutlet 128 to a plumbing system, such as a water system in a hotel orhospital.

Aquastat 127 includes a temperature sensor and an adjustable temperatureset point. Aquastat 127 is operably connected to the motor ofrecirculation pump 124, and is capable of turning the motor on or off.If recirculation temperature falls below a set point, then an internalswitch in the aquastat turns recirculation pump 124 on until therecirculation fluid temperature has reached the set point.

Typically, not all of the conditioned water provided by valve 130 isused within the plumbing system, and some of the unusedtemperature-conditioned water flows back into recirculating inlet 123 ofsystem 120. This flow returns past an aquastat 127 under the influenceof a pump 124 driven by an electric motor. Pump outlet flow isthereafter provided to the inlet of a diverting valve 126. Divertingvalve 126 provides the majority of the recirculated water through aone-way valve 129, which subsequently provides the recirculated waterthrough a tee fitting to mix with cold water from inlet 122. A portionof water from diverting valve 126 is sent out of system 120, and furtherfrom the plumbing system, by way of a recirculation outlet 125.

FIG. 7 is a cutaway representation of a valve 130 according to oneembodiment of the present invention. Valve 130 is similar in terms ofhydromechanical operation to valve 30, described earlier. A thermostatassembly 142 provides a means for quickly changing the temperature of afluid acting within a bellows 148. As the fluid contracts or expands,the bellows 148 and the fluid coact to move a rod 146 that changes theposition of a piston within a liner 134. The hydromechanical action ofthermostat 142 and piston and sleeve assembly 134 comprise a firstcontrol loop that provides temperature-conditioned water from outlet 131c. This first hydromechanical control loop is further a closed loop, aswill be appreciated by those of ordinary skill in the art. Thishydromechanical closed loop automatically mixes hot and cold water frominlets 131 a and 131 b, respectively, in a mixing chamber proximate thepiston and sleeve 134, this mixed water then flowing over the coils 144of thermostat assembly 142. After the hydromechanical control loop hasreached an equilibrium set point (i.e., a desired temperature),thermostat assembly 142 will attempt to maintain that temperature bychanging the relative mixing of hot and cold flows as required. In someembodiments, this hydromechanical loop is a proportional control loop.Any disturbances in the inputs (the hot and cold fluids) results in achange in the position of piston 134 a relative to liner 134 b, suchthat the outlet flow returns to the temperature set point after a shortperiod of time. It is recognized that in some embodiments, thehydromechanical control loop of valve 130 can have a steady state errorcharacteristic of proportionally controlled control loops.

Valve 130 further includes electric actuator 180 that also operates onthe position of piston 134 a relative to liner 134 b. As was previouslyshown and described for valve 30, in valve 130 electric actuator 180includes a motor 188 that provides a linear, translating output to apusher 152 by way of a pinion gear and worm gear combination. Aselectrical power is applied to the motor, actuator 180 moves thelocation of thermostat assembly 142 relative to the structure of valve130. In so moving thermostat assembly 142, the equilibrium set point ofvalve 130 can be changed. Further views of actuator 180 can be found inFIG. 8.

System 120 includes an electronic controller 190 in electricalcommunication with actuator 180, flow sensor 196, relay 195 of switchbox194, and temperature sensor 198. In some embodiments, electroniccontroller 190 is placed proximate to valve 130, such as on the samemounting frame 118 as shown in FIG. 6. In such embodiments, controller190 includes one or more switches (circled as 4 and 5 on FIG. 6) bywhich an operator can manually adjust the temperature of fluid flowingpast temperature sensor 198. Controller 190 further includes software(which could be logic of a PLC) for receiving and making accommodationsto the user imputs, and further for providing closed-loop control ofwater exiting valve 130 via sensor 198. In still other embodiments,controller 190 is in electrical communication with a second, remoteelectronic controller, especially a desktop controller provided within acontrol room. In such embodiments, the electronic setpoint temperaturefor system 120 can be established either remotely or locally.

System 120 further includes a switch box 94 that interfaces both withcontroller 190 and the motor of pump 124. In some embodiments, the onlyelectrical connections that are made at the installation site are forpower to the control box 194, and further for remote communication (suchas through a computer network) from a remote controller to localcontroller 190.

In other embodiments, controller 190 further includes indicator lightsfor indicating the status of the control system. Such status ispreferably either operating the electronic closed-loop control to changethe temperature of the fluid exiting valve 130, or an operational modein which controller 190 does not send a signal to actuator 180. In thelatter mode, the fluid of temperature exiting valve 130 ishydromechanically controlled in a closed loop by operation of thermostat142. Therefore, any changes in temperature or pressure at the variousvalve inputs will be compensated for by the thermostat changing theposition of the piston within the sleeve. Although what has been shownand described is a valve in which a thermostat moves a piston relativeto a sleeve, it is appreciated that other embodiments are not soconstrained, and contemplate a thermostat that is operable to controlany type of mixing valve.

When the user determines that the temperature provided to the plumbingsystem needs to be changed, then an electrical closed loop comprisingcontroller 190, software 192, actuator 180, and temperature sensor 198,can be operated to change the fluid exit temperature. In order to changethe equilibrium temperature of water exiting system 120, in someembodiments the user at the remote site uses a key to unlock anelectrical switch that activates the closed-loop control. In furtherembodiments, in order for the electronic loop to become active, thereshould be sufficient flow of fluid past flow sensor 196, and furtherrecirculation pump 124 should not be operating. In some embodiments, theflow sensor 196 is a paddle-type electrical switch that is deflectedaway from a normal position if flow through sensor 196 exceeds apredetermined value. In some embodiments of the present invention, flowsensors are chosen to actuate (i.e., flip positions) at predeterminedflow levels of 4, 6, 8 and 10 gallons per minute, depending upon thesize of the plumbing system being provided with temperate-conditionedfluid. it is appreciated that these values are by way of example only,and not to be considered as limiting.

In yet further embodiments, flow sensor 196 can be any type of sensorthat is capable of providing an electrical signal to controller 190 toindicate that flow is exceeding a predetermined limit. For example, insome embodiments, flow sensor 196 is a sensor (such as a turbine flowmeter) that provides a variable signal corresponding to a range offlows, unlike some paddle-type switches that operate in terms of on andoff. In yet other embodiments, flow sensor 196 can be a pressure sensor,especially a pressure differential sensor, that is responsive to flowpast sensor.

In yet other embodiments, the electronic control loop will not becomeactive unless pump 124 is operating. In such systems, controller 190receives a signal from switch box 194 that indicates whether or notpower is being provided to pump 124. It is further understood that inyet other embodiments, the sensing of pump motor electrical power can bereplaced with another flow sensor that receives flow from recirculationinput 123. In such systems, the electronic control loop cannot go activeif the recirculated flow is above a predetermined level. In someembodiments, control box 194 includes a relay 195 that is in electricalcommunication with flow switch 196. In such embodiments, both flow outof system 120 must exceed the predetermined level expressed by flowswitch 196, and further the motor of pump 24 must not be powered tooperate the pump.

FIGS. 10A and 10B depict various states of a graphical user interface100 according to one embodiment of the present invention. FIG. 10A showsGUI 100 in a first mode of operation. This GUI, shown at the location ofthe remote controller, informs the operator that there is apredetermined time delay between the remote logic and controller 190. Insome embodiments, this time delay is about five seconds. Further, theGUI 100 informs the operator that the remote controller has apredetermined shut-off with regards to the ability to remotely set theequilibrium system of 120. This feature helps prevent inadvertentchanges in temperature should the remote user leave the remotecontroller program to perform other activities. GUI 100 includesinstructions to the remote operator that the recirculation pump 124needs to be turned off prior to attempting to set a new equilibriumtemperature. Further, if there is insufficient demand on the plumbingsystems such that flow switch 196 does not indicate flow above apredetermined level, then the operator should create sufficient demandin the plumbing system until the flow sensor indicates sufficient flow.

GUI 100 shows that the remote operator is provided with a readout of thecurrent set point, and further of the actual temperature being sensed bysensor 198. In addition, there are input switches, such as by touchscreen, to change the set point up or down. Further switches areprovided to operate the remote controller either in the set mode (inwhich the equilibrium temperature is reset) or to operate in normalfashion (i.e., with the hydromechanical closed loop in control of valveexit temperature). Further, the operator can turn off the recirculationpump. Readouts are also provided for temperatures provided at the valvehot inlet and cold inlet, and indicators as to whether or not there issufficient FLOW through sensor 196, and whether any alarm has beentriggered. GUI 100′ of FIG. 10B shows the remote controller softwarestatus after it has synchronized with remote controller 190.

FIG. 11 is a schematic representation of an electrical system 219 for aflow system 220 according to another embodiment of the presentinvention. System 220 includes an electronic controller 290 such as aNANODAC™ electronic controller that provides electronic control of thetemperature exiting valve 230 by way of closed loop electronic control.Controller 290 further includes software and a user interface for dataacquisition and recording.

While the inventions have been illustrated and described in detail inthe drawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain embodiments have been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

1. An apparatus for providing thermostatically-controlled fluid,comprising: a hot fluid inlet and a cold fluid inlet; a valve movableover a range of positions to vary the relative mixing of fluid receivedfrom the hot inlet with fluid received from the cold inlet; a thermostatoperably connected to said valve to move said valve in response to thetemperature of the mixed fluid; and an electrical actuator operablyconnected to said valve to move said valve in response to an electricalsignal.
 2. The apparatus of claim 1 wherein the electrical signal movessaid actuator to a position, and the actuator substantially retains thatposition when the electrical signal is removed.
 3. The apparatus ofclaim 1 wherein said valve moves linearly in a direction, and saidthermostat moves said valve in the direction and said actuator includesa member that moves in the direction.
 4. The apparatus of claim 1wherein said actuator is operably connected to said valve by saidthermostat.
 5. The apparatus of claim 1 wherein said valve is biased ina direction by a spring and said thermostat moves said valve in anopposite direction.
 6. The apparatus of claim 1 wherein said electricalactuator includes an electric motor.
 7. A method for providingthermostatically-controlled fluid, comprising: providing a thermostat,an electrical actuator, a source of hotter fluid, a source of colderfluid, and a repositionable mixing valve; mixing the hotter fluid andthe colder fluid with the mixing valve; flowing the mixed fluid aroundthe thermostat; repositioning the mixing valve by the thermostat inresponse to said flowing; and repositioning the thermostat by theactuator.
 8. The method of claim 7 wherein said providing includes aspring to bias the thermostat to a position, and said repositioning thethermostat is by changing the bias on the spring.
 9. The method of claim7 wherein said repositioning the mixing valve is with a first innerclosed automatic control loop and said repositioning the thermostat iswith a second outer closed automatic control loop.
 10. The method ofclaim 7 wherein said providing includes an electronic controllerreceiving an electrical signal from a temperature sensor, and saidrepositioning the thermostat is by the controller in response to thesignal.
 11. A system for providing thermostatically-controlled fluid,comprising: a hotter fluid inlet and a colder fluid inlet; athermostatically controlled mixing valve receiving fluid from both thehotter inlet and the colder inlet and providing mixed fluid at a fluidexit; a flow sensor located downstream of the fluid exit and providingan electrical signal responsive to the amount of fluid flowing past saidflow sensor; a recirculated fluid inlet; and a recirculation pumpreceiving fluid from the recirculated fluid inlet, said pump beingdriven by an electric motor, said motor operating in response to saidsignal.
 12. The system of claim 11 which further comprises an electricalrelay for providing power to said motor, wherein the state of said relayis responsive to said signal.
 13. The system of claim 11 wherein saidflow sensor is a flow-actuated electrical switch.
 14. The system ofclaim 11 wherein said flow sensor provides an electrical signalresponsive to flow exiting from said mixing valve.
 15. The system ofclaim 11 wherein said flow sensor provides an electrical signalresponsive to the fluid pressure proximate to the exit of said mixingvalve.
 16. The system of claim 11 wherein at least a portion of fluidexiting said recirculation pump is mixed with fluid from said colderfluid inlet and provided to said mixing valve.
 17. The system of claim11 which further comprises an electrical actuator operably connected toan electronic controller, said actuator operably connected to saidmixing valve to change the temperature of the fluid exiting said mixingvalve.
 18. The system of claim 17 wherein said controller receives asecond electrical signal responsive to power provided to said motor. 19.The system of claim 18 wherein said controller prohibits operation ofsaid actuator if said pump is powered.
 20. The system of claim 17 whichfurther comprises a user-modifiable temperature adjustment, and whereinsaid controller is responsive to a signal received from said adjustmentto change the temperature of fluid exiting said mixing valve.
 21. Thesystem of claim 20 wherein said adjustment is located proximate to saidmixing valve.
 22. The system of claim 20 wherein said adjustment isadapted and configured for manipulation by the hand of the user.
 23. Thesystem of claim 20 wherein said controller is a first controller capableof receiving instructions from a remotely located second controller,said second controller capable of changing the temperature of fluidexiting said mixing valve.
 24. The system of claim 23 wherein saidsecond controller includes software capable of changing the temperatureof fluid exiting from said mixing valve, and said software includes atimer for disabling the software capability.
 25. A method for providingtemperature-controlled fluid, comprising: providing an electroniccontroller in electrical communication with an electrical actuator, asource of hotter fluid, a source of colder fluid, and an actuatablemixing valve; mixing the hotter fluid and the colder fluid with themixing valve to provide mixed fluid at a temperature; changing thetemperature of the mixed fluid with the actuator by the controller; andmaintaining the changed temperature if the electrical communication isbroken.
 26. The method of claim 25 wherein the actuator isrepositionable and holds a fixed position if electrical communication isbroken.
 27. The method of claim 25 wherein said providing includes athermostat operably connected to the mixing valve, and said maintainingis by the thermostat.
 28. The method of claim 25 wherein said providingincludes a thermostat responsive to the temperature of the mixed fluid,and which further comprises varying the temperature of the mixed fluidby the thermostat.
 29. The method of claim 28 wherein the mixing valveis repositionable, and which further comprises repositioning the mixingvalve by the thermostat or by the actuator.
 30. The method of claim 28wherein said changing is by moving the thermostat with the actuator.